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<H1 ID="S4"><SPAN CLASS="chapnum">4</SPAN> Transmitted Characters</H1>
<H2 ID="S4.1">General</H2>
<P>This chapter describes the characters generated by the VT102 keyboard.
The keys are divided into three groups: standard keys, function keys, and
numeric keypad keys.</P>
<H2 ID="S4.2">Standard Keys</H2>
<P>The keyboard generates American Standard Code for Information Interchange
(ASCII) characters. The standard keys (<A HREF="figure4-1.html">Figure 4-1</A>) generate
lowercase ASCII characters when neither <SPAN CLASS="keyname">SHIFT</SPAN> or <SPAN CLASS="keyname">CAPS LOCK</SPAN> are
down. These keys generate uppercase ASCII characters when either <SPAN CLASS="keyname">SHIFT</SPAN> or <SPAN CLASS="keyname">CAPS LOCK</SPAN> key are down. <SPAN CLASS="keyname">CAPS LOCK</SPAN> does not affect the
nonalphabetic keys.</P>
<H2 ID="S4.3">Function Keys</H2>
<P>The function keys (<A HREF="figure4-2.html">Figure 4-2</A>) generate characters defined by the computer
software or communication system. The following paragraphs describe
the function keys.</P>
<H3 ID="S4.3.1">BREAK/HERE IS</H3>
<P>This key generates a break defined by the computer system when the
break enable feature is on. This feature does not affect other key sequences
using <SPAN CLASS="keyname">BREAK</SPAN>.</P>
<P>Hold down <SPAN CLASS="keyname">SHIFT</SPAN> and press <SPAN CLASS="keyname">BREAK</SPAN> to generate a long break disconnect.
A long break disconnect usually disconnects the terminal from the communication
line. See <A HREF="chapter6.html#S6.2.3">Break</A> in <A HREF="chapter6.html">Chapter 6</A> for more information about breaks
and long break disconnects.</P>
<P>Hold down <SPAN CLASS="keyname">CTRL</SPAN> and press <SPAN CLASS="keyname">HERE IS</SPAN> to transmit the answerback message.
See <A HREF="chapter3.html">Chapter 3</A> for more information about the answerback feature.</P>
<H3 ID="S4.3.2">Cursor Control Keys</H3>
<P>In ANSI mode, with alternate (application) keypad mode selected, the cursor
keys generate either application or cursor control sequences. Cursor
key mode selects the type of sequence.</P>
<P>With numeric keypad mode selected, the cursor keys generate ANSI cursor
commands. The computer selects both cursor key mode and keypad
mode. See <A HREF="chapter5.html#S5.5.2.14">Cursor Key Character Selection</A> in <A HREF="chapter5.html">Chapter 5</A> for more information.</P>
<P>In VT52 mode, the cursor keys only generate VT52 cursor control sequences.
<A HREF="table4-1.html">Table 4-1</A> lists the ANSI and VT52 compatible cursor key characters.</P>
<H3 ID="S4.3.3">Control Character Keys</H3>
<P><A HREF="figure4-3.html">Figure 4-3</A> shows the keys that generate control characters. You can generate
control characters in two ways.</P>
<UL>
<LI>Hold down <SPAN CLASS="keyname">CTRL</SPAN> and press any unshaded key in <A HREF="figure4-3.html">Figure 4-3</A>.</LI>
<LI>Press any shaded key in <A HREF="figure4-3.html">Figure 4-3</A> without using <SPAN CLASS="keyname">CTRL</SPAN>. These dedicated
keys generate control characters without the use of <SPAN CLASS="keyname">CTRL</SPAN>.</LI>
</UL>
<P><A HREF="table4-2.html">Table 4-2</A> lists the control characters generated by the keyboard. Different
computer systems may use each control character differently.</P>
<P CLASS="note">NOTE: The VT102 generates some control characters differently than
previous DIGITAL terminals. <A HREF="table4-3.html">Table 4-3</A> lists the changes.</P>
<H2 ID="S4.4">Numeric Keypad Keys</H2>
<P>These keys generate characters selected by the ANSI/VT52 feature and
alternate (application) keypad mode. The computer selects application
keypad mode. See <A HREF="chapter5.html#S5.5.2.15">Keypad Character Selection</A> in <A HREF="chapter5.html">Chapter 5</A> for more information.</P>
<P>In numeric keypad mode, the numeric keypad generates the numeric,
comma, period, and minus sign characters used by the main keyboard. In
application keypad mode, the numeric keypad generates control functions.
<A HREF="table4-4.html">Table 4-4</A> lists the characters generated by the numeric keypad.</P>
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